Various devices have been developed in the prior art to facilitate fishing with a baited hook or lure at depths down to a few hundred feet below the surface. Such devices generally comprise a frame with a shaped plate or hydrofoil with a trolling line and a fishing line connected to the frame. The hydrofoil assumes a diving attitude during trolling with the fishing line trailing behind a boat. An abrupt pull on the fishing line, as in the case of a strike by a fish, causes a shift in the attitude of the hydrofoil and results in the device climbing to the surface. Such devices are sometimes known as trolling planes, diving planes or downriggers. Whatever the name, there has been a high degree of refinement in design to obtain improved performance.
The Cooledge et al U.S. Pat. No. 2,235,868 discloses a wire frame structure with a lower portion turned up at its rear end and attached to a plane; the forward end in front of the plane is arched upwardly and rearwardly to an elbow at which it extends downwardly and attaches to the plane. A trolling line is attached by a loop through the wire frame and the loop is movable along the arched portion thereof. The fishing line is attached to the rear of the plane.
The Dawson U.S. Pat. No. 3,667,148 discloses a trolling plane similar to that described above but having the fishing line pass through an opening in the plate and being attached to the wire frame adjacent its connection with the plate. The Heili U.S. Pat. No. 3,863,382 discloses a trolling plane having a hydrofoil or "vane" rigidly mounted between the spaced ends of the wire frame. The vane is formed as a pair of V-shaped channels to provide a desired hydrodynamic effect.
Other prior art trolling planes of the type described above are disclosed in the following U.S. Pat. Nos. Collins 3,466,787; Zaharis 3,708,904; Staaden 4,128,959; and Davis 4,199,891.
A general object of this invention is to provide an improved trolling plane which overcomes certain disadvantages of the prior art.